The present invention relates to trays for holding dental or medical instruments and, more particularly, to dental or medical instrument cassettes that permit the storage and sterilization of instruments.
Working trays or cassettes that store dental or medical instruments and permit their sterilization are known in the art. Such cassettes typically retain the instruments within instrument-holding notches for use during a procedure. After completion of the procedure, the cassette is closed and placed in an ultrasonic cleaner so that the contaminated instruments can be cleaned. After cleaning, the cassette (with its instruments) is rinsed, wrapped in an autoclave wrap, and then placed in an autoclave to sterilize the instruments. The cassettes are typically of a size and shape that permit stacking so that more than one cassette can be sterilized at the same time. Although larger, more expensive autoclaves that hold multiple cassettes are available, the autoclaves most commonly used by individual practitioners permits only a very small number of cassettes to be sterilized in one batch. With practitioners seeing up to 30 patients in one day, it becomes quite time-consuming to run many sterilization cycles of the autoclave and only sterilize a small number of instruments per cycle. Thus, there is a need in the field for an instrument cassette that permits greater efficiency in the sterilization process.
One way to increase efficiency is to reduce the size of the cassette so that more cassettes can fit in the autoclave. However the size of the cassette is often dictated by the number and size of the instruments that are needed for a procedure. Typically, 12-18 instruments are arranged side by side in the bottom tray of the cassette so that the cassette must be about 10-12 inches long in order to hold all the instruments.
One solution for decreasing the size of the cassette without decreasing its capacity is found in U.S. Pat. No. 4,930,660 to Porteous. That patent discloses an instrument cassette in which both the lower tray and the upper cover of the cassette are used for storing instruments. One advantage of this design is that the cassette can be smaller in size since the top half can accommodate half of the instruments. The instruments are held in place by the convolutions of a coil spring placed laterally across each cassette half. Although the coil spring is adequate for holding instruments of the same size, it cannot accommodate larger instruments, such as forceps, except at the risk of permanent deformation of the spring.
U.S. Pat. No. 4,854,475 to Riihimaki et al. discloses an instrument cassette that is provided with flexible, compressible instrument-retaining members that can receive medical or dental instruments of various shapes and sizes. The instruments are held in place by a flexible, compressible clamping member mounted to the lid of the cassette. Although the clamping member functions adequately to hold the instruments in place, two hands are required to manipulate the clamping member and remove it from the lid, making it cumbersome to use. Thus, there is also a need in the field for an instrument cassette that can hold instruments of various sizes and which has an instrument retaining member that can be easily manipulated.